I noticed yesterday someone took a chunk out of the tail fin of my 8" gold severum. It was either the 12" pleco or the 12" african knife fish? The pleco gets a slice of zuchinni every day and the knife gets a whole earthworm daily. I don't know which one is guilty. The tank is 150, also has 2 tinfoil barbs (8"), 3 blood parrots.